Finished ripping out the fixtures and disconnecting the cast iron tub in my third floor bathroom yesterday. I am planning on installing a subway/hex tile floor, where there currently is very old (probably 1970s) vinyl flooring installed. Will likely keep the cast iron tub, but add a shower attachment to it - we need to move the plumbing to the other side of the room - I'll be hiring a plumber for that. Re: the floor, we originally planned on removing the vinyl floor, putting in cement board on existing subfloor, then tiling. The vinyl is not cooperating with plan A.

I used a heat gun to start pulling up the vinyl, but all that comes up is the top layer, and the foamy/glue back of the vinyl stays behind. Additional elbow grease with the scraper only leads to splintering up a couple of millimeters of the subfloor. I did about two square feet in this manor before deciding to check with cooler heads whether I should keep going as planned. If I keep at it, the subfloor is going to be pretty scraped up and not level.

I'm considering the following alternatives:

1) Give up on pulling up vinyl, and apply thinset to vinyl, install cementboard, continue as planned with tiling. (Downside here is lower quality bond and built up floor right?)

2) Keep going and see how bad the sub floor looks when I'm done. Will likely require some form of self leveling compound before applying cement board. Is this feasible?

3) Use a saw to pull up and replace entire subfloor. I am very uncomfortable doing this.

Any feedback would be appreciated. I am leaning towards #1. A couple other issues:

1) There is a 1# bow in the floor from wall to wall as it is, so I am considering a leveling compound anyway. How much does this add to height? Can I still thinset and cement board effectively over top of a leveling compound?

2) No matter what, I am going to have to shorten my bathroom door - it barely clears the vinyl as it is.

Assuming you have no open flames anywhere, get a spray bottle and a 1/2 gallon can of lacquer thinner. Have good ventilation in the room (open window, not a fan) Have a helper spray a line liberally to coat the underside of a vinyl pices. Push the scraper (long handle variety) hard into the vinyl ... it will begin to come up much more easily without ripping the subfloor. Repeat acorsss the room. Remove vinyl chunks to outside because they will be soaked with thinner.

Continue until all vinyl is gone. Make sure you have no big chunks left. Do the plumbing, repair the subfloor. Proceed to tile.

Hmm not cool. I can't get to the bottom of vinyl without major gouging into the vinyl strips I cut with a box cutter. There is no daylight ever, between the bottom of the vinyl and the wood. Nor do I believe the design top of the vinyl will allow any solvent to permeat. Can you describe this part in greater detail or does that change your approach?

I used a heat gun to start pulling up the vinyl, but all that comes up is the top layer, and the foamy/glue back of the vinyl stays behind. Additional elbow grease with the scraper only leads to splintering up a couple of millimeters of the subfloor. I did about two square feet in this manor before deciding to check with cooler heads whether I should keep going as planned. If I keep at it, the subfloor is going to be pretty scraped up and not level.

I think I hear you saying there are TWO layers on your floor. If you are already into the subfloor level, the thinner will release that level as you push the scraper through it. The minor imperfections are not a problem because your cement board will provide the smooth floor substrate you need. You could get anal retentive and sand the subfloor but why?

I have done this. It works. Did it on cement slab and on wood subfloor.

That is what I recommend if you feel determined to remove the vinyl. Alternatively, you could simply leave the floor (after applying leveling compaound to your gouges) then installing a transition strip at the doorway to make up for the height variation.

If you are going to have to get into the floor anyway to do the new plumbing and as much work as this sounds removing the flooring, I would go for ripping it up and having a good look at what you have below. This way you will also know the new sub floor is installed properly to take the tile. Most 40 year old bathrooms have something interesting to find under the floor.

That would be my opinion based on the information provided. Sometimes you have to weigh the cost of materials against the time spent trying to save them.

I think I hear you saying there are TWO layers on your floor. If you are already into the subfloor level, the thinner will release that level as you push the scraper through it. The minor imperfections are not a problem because your cement board will provide the smooth floor substrate you need. You could get anal retentive and sand the subfloor but why?

I have done this. It works. Did it on cement slab and on wood subfloor.

That is what I recommend if you feel determined to remove the vinyl. Alternatively, you could simply leave the floor (after applying leveling compaound to your gouges) then installing a transition strip at the doorway to make up for the height variation.

So many choices, so much fun.

I believe the vinyl was laid directly on the subfloor, ie no underlayment b

Go to the 2 x 2 area you already have clear of vinyl. Take a utility knife, a wood chisel or a hand saw of some type. Try to cut a small square in the floor about 3/8" to 1/2" deep. If there is underlayment between the vinyl and subfloor at this depth you should cut through it. Generally the underlayment is nailed or stapled to the floor not glued. What is the age of your house? Do you know if your subfloors are plywood, OSB or tongue and groove boards? If you can determine this you may be able to tell by looking at the underside of the floor and comparing it to the top side without cutting anything.
You mentioned you have a 1" sag in the middle of the floor. Can you tell why? You said you are going to move plumbing. Is there a basement or crawlspace under this room? Or will you have to pull subfloor to make plumbing changes? As suggested if you have to cut subfloor to move plumbing maybe removing subfloor and correcting your sag is the way to get everything straightened out to start fresh.

I always hate covering up crap. But that is just me. A little anal retentive.